Footwear, footwear adjustment mechanisms and the manufacturing thereof

ABSTRACT

Footwear has a rear portion and a front portion having at least one gap therebetween, wherein relative positions of the rear portion and the front portion define a size of the footwear. A rail is configured with the rear portion and a slider is configured with the front portion, the slider engaging the rail. The rail provides multiple distinct and discrete positions for the slider, and a position of the slider in the rail determines a size of the at least one gap. The front and rear portions comprise molded plastic, and the rail is molded in the rear portion.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 62/950,382, filed Dec. 19, 2019, the entire contents of which are hereby fully incorporated herein by reference for all purposes.

COPYRIGHT STATEMENT

This patent document contains material subject to copyright protection. The copyright owner has no objection to the reproduction of this patent document or any related materials in the files of the United States Patent and Trademark Office, but otherwise reserves all copyrights whatsoever.

FIELD

This invention relates to footwear, and, more particularly, to adjustment mechanisms used with footwear, including adjustment mechanisms that are molded as part of the footwear.

BACKGROUND

Components (e.g., the soles, the uppers, the buckles, etc.) that make up footwear are typically produced in mass volume using molding, die cutting, extrusion, and other manufacturing processes. The components are made separately in bulk and then manually configured together (e.g., sewn and/or glued) to form a final product.

Secondary assembly and labor account for a significant percentage of the overall cost of footwear. For example, sewing and/or gluing the uppers onto the soles, sewing and/or gluing the buckles onto the uppers, and configuring the buckles together all add additional cost to the final product.

It is desirable and an object hereof to provide footwear with reduced secondary assembly and labor costs. It is also desirable and an object hereof to provide a manufacturing process that reduces the secondary assembly required to produce the design of footwear.

SUMMARY

The present invention is specified in the claims as well as in the description.

One general aspect includes a shoe comprising: a rear portion and a front portion having at least one gap therebetween, wherein relative positions of the rear portion and the front portion define a size of the shoe; and a rail configured with the rear portion; a slider configured with the front portion, the slider engaging the rail, wherein the rail provides multiple distinct and discrete positions for the slider, and wherein a position of the slider in the rail determines a size of the at least one gap, and wherein the front portion and the rear portion comprise molded plastic, and wherein the rail is molded in the rear portion.

Implementations may include one or more of the following features, alone or in combination(s):

-   -   A shoe wherein the rail has a circular cross section; and/or     -   A shoe wherein the rail includes a plurality of ridges, said         ridges defining said multiple distinct and discrete positions         for the slider; and/or     -   A shoe further comprising a sole, and wherein the rail is at a         non-zero angle to a base of the sole; and/or     -   A shoe further comprising a sole, and wherein the rail is         parallel to a base of the sole.

The following numbered embodiments also form part of the invention.

Below is a list of device (shoe) embodiments. Those will be indicated with a letter “S”. Whenever such embodiments are referred to, this will be done by referring to “S” embodiments.

-   -   S1. A shoe comprising:     -   a rear portion and a front portion having at least one gap         therebetween, wherein relative positions of the rear portion and         the front portion define a size of the shoe; and     -   a rail configured with the rear portion; and     -   a slider configured with the front portion, the slider engaging         the rail,     -   wherein the rail provides multiple distinct and discrete         positions for the slider, and     -   wherein a position of the slider in the rail determines a size         of the at least one gap, and     -   wherein the front portion and the rear portion comprise molded         plastic, and     -   wherein the rail is molded in the rear portion.     -   S2. The shoe of embodiment S1, wherein the rail has a circular         cross section.     -   S3. The shoe of any of the embodiment(s) S1-S2, wherein the rail         includes a plurality of ridges, said ridges defining said         multiple distinct and discrete positions for the slider.     -   S4. The shoe of any of the embodiment(s) S1-S3, further         comprising a sole, and wherein the rail is at a non-zero angle         to a base of the sole.     -   S5. The shoe of any of the embodiment(s) S1-S4, further         comprising a sole, and wherein the rail is parallel to a base of         the sole.

The above features along with additional details of the invention, are described further in the examples herein, which are intended to further illustrate the invention but are not intended to limit its scope in any way.

BRIEF DESCRIPTION OF THE DRAWINGS

Various other objects, features and attendant advantages of the present invention will become fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein:

FIGS. 1A-1C show aspects of footwear with an adjustment mechanism according to exemplary embodiments hereof;

FIGS. 2A-2L, 3A-3C and 4A-4D show aspects of adjustment mechanisms according to exemplary embodiments hereof;

FIGS. 5A-5C show aspects of an alternate adjustment mechanism according to exemplary embodiments hereof;

FIGS. 6A-6B show aspects of footwear with an adjustment mechanism according to exemplary embodiments hereof; and

FIG. 7 shows an alternate adjustment mechanism according to exemplary embodiments hereof.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EXEMPLARY Embodiments

FIGS. 1A-1B show an article of footwear 100 incorporating an adjustment mechanism according to exemplary embodiments hereof. The adjustment mechanism may be used to tighten and/or loosen the fit of the footwear when worn. The adjustment mechanism is preferably molded with the footwear to reduce secondary assembly requirements of the footwear.

As used herein, footwear may include any type of footwear including, e.g., athletic shoes, dress shoes, casual shoes, high heel shoes, sandals, clogs, boots, slippers, etc. For the purposes of this disclosure however, embodiments hereof will be described with respect to a single article of footwear, specifically, a rubber or plastic sandal.

In addition, while the description describes footwear for a right foot, it is understood that the embodiments described herein also pertain to a corresponding left foot article of footwear when a pair of footwear is provided. The left article of footwear is generally symmetric and a mirror of the right article of footwear. It is also understood that the embodiments described herein may pertain to any type of footwear.

With reference again to FIGS. 1A-1B, footwear 100 (e.g., a plastic sandal) includes a sole 114 on the bottom with an upper 116 on the top, therebetween providing a space for the wearer's foot. The footwear 100 includes a front 106 (also referred to as the toe), a back 108 (also referred to as the heel), a left side 110 (and a right side 112 (also referred to as the outer side).

The upper 116 includes a front upper portion 122 and a back upper portion 124. The front upper portion 122 generally covers at least a portion of the bridge and/or the toes of the wearer's foot, and the back upper portion 124 generally extends around at least a portion of the wearer's heel when worn. The back upper portion 124 may also be referred to as a heel strap, a heel support, or a back strap.

A top opening 126 is formed between the front upper portion 122 and the back upper portion 124 through which the wearer's ankle may extend when worn. The fit of the footwear 100 may be adjusted, e.g., by changing the relative positions of the front upper portion 122 and the back upper portion 124. For example, the fit of the footwear 100 may be adjusted by moving the front and back upper portions 122, 124 towards or away from one another (to reduce or expand the size of the opening 126 and thereby tighten or loosen the footwear 100).

The front upper portion 122 may include a back edge 128, and the back upper portion 124 may include a front edge 130. The back edge 128 and front edge 130 may overlap or have a gap G therebetween. In the drawings the gap G is shown by two dashed lines. The size of the top opening 126 may be reduced or expanded by, respectively, decreasing or increasing the distance between the back edge 128 and front edge 130 (or by adjusting the overlap between the back edge 128 and front edge 130). That is, the size of the top opening 126 may be reduced or expanded by, respectively, decreasing or increasing the size of the gap G.

For the purposes of this specification, the adjustable portion will be described in relation to the right side 112 of the footwear which, for the right foot, is on the outside of the footwear. Preferably, the front upper portion 122 and the back upper portion 124 are joined on the inside (the left side 110, as shown in FIG. 1A). However, it is understood however that an overlap or gap may also (or instead) be formed on the left side 110 (or inside) of the footwear 100.

In exemplary embodiments hereof, the footwear 100 may include an adjustment mechanism that may decrease and/or increase the size of the gap G and/or adjust the overlap between the back edge 128 and front edge 130, thereby reducing and/or expanding the size of the top opening 126 and adjusting the fit of the footwear 100.

With reference to FIGS. 1A-1B and 2A-2B, the adjustment mechanism may include a track 134 (also referred to as a rail). The track 134, shown in greater detail in FIGS. 3A-3C, may be smooth or, preferably, include one or more ridges 136 (shown by the lines in the drawings) which define one or more notches or segments 138. An end piece 140 defines an end of the track 134, to prevent the slide mechanism from coming too far forward and off the track.

With reference to FIGS. 2A-2B, the footwear 100 may include a tab 202 (not shown in FIGS. 1A-1B) attached to the back edge 128 of the front upper portion 122. The tab 202 includes a mount portion (not shown in FIGS. 1A-1B) which engages slidably with the track 134.

Aspects of an exemplary tab 202 are shown in greater detail in FIGS. 2C-2K.

In an alternate embodiment, e.g., as shown in FIG. 2L, a tab 222 may have a portion 224 with a hole 226 formed therein. The hole 226 may match a corresponding hole 228 on a part of the back edge 128, and the tab may be connected e.g., using a stud 230 or the like. As should be appreciated, such a connection requires no stitching or gluing, thereby reducing the cost and/or production process.

The ridges or segments of the track 134 define distinct and discrete engagement positions for the mount portion. The track 134 preferably has a circular cross section (e.g., as shown in FIG. 3C), where the diameter of the track 134 in the segments 138 is less than the diameter of the track 134 at the ridges 136. The diameter of the end piece 140 is preferably sufficiently large to prevent movement of the mount portion of the tab beyond the end of the track 134.

The track 134 may be configured with the back upper portion 124, and the mount 204 may be configured with the front upper portion 122. Alternatively, the positions of the track and mount may be reversed.

The mount 204 may be slidably configured with the track 134 to move laterally along the track's length in either direction as depicted by the arrow AA′ in FIG. 3B.

As shown in FIG. 4A (along cut-lines B-B in FIG. 1B), a base 406 extends between the rail 134 and the outer surface 142 of the footwear 100. The base 406 may extend continuously along the longitudinal length of the rail 134, or the base 406 may be sectional with different sections positioned at distinct locations along the length of the rail. It is understood that the base 406 may extend in any areas along the rail 134 and in any number of sections.

The rail 134 may include a generally circular cross-section as shown, although other cross-sectional shapes such as oval, square, rectangular, triangular, octagonal, trapezoidal, and/or other shapes are contemplated and may also be used.

As shown in FIG. 4B (and FIGS. 2C-2K), the mount 204 may comprise a slider that includes a ring-shaped portion or ring 206 or other appropriate form with an inner opening 208 that has a cross-section that generally conforms to the cross-section of the rail 134. The cross-section of the rail 134 may fit within the cross-section of the inner opening 208, thereby configuring the slider with the rail 134. The slider's ring 206 may include a slot 210 that may accommodate the base 406 in the areas where the ring and the base 406 may overlap. The slot 210 may preferably be sized to accommodate the base 406 while retaining the rail 134 within it.

The configuration in FIG. 4C corresponds to a position of the slider in a segment 138 of the rail 134. As shown in FIG. 4C, the outer circumference of the rail 134 may fit snugly within the opening of the slider with enough friction to hold the slider's position unless adequate force is applied to move it along the rail 134. The configuration in FIG. 4D corresponds to a position of the slider at or against a ridge 136 of the rail 134. At a ridge 136, the outer circumference of the rail 134 exceeds the inner circumference of the ring 206, thereby preventing unassisted movement of the mount 204 past the ridge 136. A ridge 136 thus acts to prevent free movement of the mount 204. As explained, the rail 134 and/or mount 204 are made from plastic or other material that may be bent or otherwise shaped to allow for movement of the mount 204 past a ridge 136 with a sufficient amount of force. Those of skill in the art will understand, upon reading this description, that the amount of force needed should be suitable to prevent unassisted movement while the footwear is in use, but should not be so much as to prevent any movement.

The tab 202 may include a slide locking mechanism 212 (e.g., in FIG. 2K) including at least one tooth 214 (that will engage in the ridges on the track.

As described above with reference to FIGS. 3A-3C, the rail 134 may include at least one notch or segment 138 (e.g., saw-tooth) positioned along its length that may engage the slider. When engaged, the notch or segment 138 may preferably hold the slider at its position until adequate force is applied to the slider to overcome the ridge 136 that bounds the notch or segment 138. The ridge 136 (and/or the rail 134 and/or the slider) may preferably comprise a compressible material that may release the slider from the notch or segment 138 when an adequate force is applied. Otherwise, the notches or segment 138 may serve to hold the slider at a desired adjustment position along the rail 134.

As described, the rail 134 is raised above the surface of the footwear 100. In other exemplary embodiments hereof, as shown, e.g., in FIGS. 5A-5C, the track 134 may comprise a slot 514 configured in the outer surface of the back upper portion 124 (in the same or a similar location to the track 134 in FIGS. 1A-1B). The slot 514 may include a lower recess 516 that runs the length of the slot 514 with a width greater than that of the slot 514. The recess 516 may generally terminate the bottom of the slot 514. A cross-section of the slot 514 and recess 516 is shown in FIG. 5A.

The recess 516 may include a generally rectangular cross-section as shown, although other cross-sectional shapes such as circular, oval, square, triangular, octagonal, trapezoidal, and/or other shapes are contemplated herein and may also be used.

As shown in FIG. 5B, the mount 204 may comprise a post 518 that includes a head 520, with the cross-section of the post 518 and head 520 generally conforming to the cross-section of the slot 514 and recess 516, respectively. The cross-section of the post 518 and head 520 may fit within the cross-section of the slot 514 and recess 516 thereby configuring the post 518 and head 520 with the slot 514 and recess 516.

As shown in FIG. 5C, the post 518 and the head 520 may fit snugly within the slot 514 and recess 516 with enough friction to hold their position unless adequate force is applied to move them along the slot 514.

The slot 514 and/or recess 516 may include at least one notch positioned along their length that may engage the post 518 and/or head 520, respectively. The details of the notch may resemble the details of the notch described above in relation to the rail 134.

A person of ordinary skill in the art will understand that the above embodiments of the track and the mount 204 formed as a rail 134 and a slider, and as a slot/recess 214/216 and a post/head 218/220 are meant for demonstrational purposes and that the track and/or the mount 204 may be provided in other forms that may accomplish the same or similar outcomes. It is also understood that the scope of the adjustment mechanism, the track, the mount 204 and the footwear 100 is not limited in any way by the form of the adjustment mechanism.

The track 134 is shown in FIGS. 1A-1B at a non-zero angle relative to the sole 114. It should be appreciated that the angle of the track 134 may vary depending, e.g., on the style and shape of the footwear. For example, as shown in FIG. 1C, the track 134 may be substantially parallel to the sole 114.

Example

FIGS. 6A-6B show an exemplary plastic molded shoe according to embodiments hereof.

FIG. 6A shows the mount at a position P1 on the track with a resulting gap G1 between X and Y, and FIG. 6B shows the mount at a position P2 on the track with the resulting gap G2 between the front edge of the back upper portion and the back edge of the front upper portion. As shown in the drawings, the size of the gap G1 is greater than the gap G2.

As the mount 204 moves from position P1 to position P2, the front upper portion is moved closer to the back upper portion, the size of the gap is reduced (and/or the overlap is increased), the opening is reduced, and the footwear is tightened. Conversely, as the mount moves from position P2 to position P1, the front upper portion is moved away from the back upper portion, the size of the gap is increased (or the overlap is decreased), the opening is expanded and the footwear 100 is loosened.

While FIGS. 6A and 6B depict the front upper portion moving towards and away from the back upper portion during this process, and the back upper portion remaining somewhat stationary, it is understood that the back upper portion may also move. However, it may be preferable that the footwear be crafted so that the majority of the adjustment movement occurs with the front upper portion. It may also be preferable that the front upper portion and/or the back upper portion comprise a material that may stretch to facilitate movement of the portions.

End of Example

FIG. 7 shows an alternate adjustment mechanism according to exemplary embodiments hereof. As shown in FIG. 7 , the rail 734 may be formed separately (e.g., as a separate molded component). The rail 734 may include a slide portion 736 that may be inserted in a corresponding slot formed in the shoe.

Manufacturing

In exemplary embodiments hereof, the footwear 100 and the associated adjustment mechanisms may be manufactured in combination to reduce secondary assembly and labor costs normally associated with producing footwear.

For example, in some embodiments, the elements of the footwear 100 (e.g., the front upper portions and/or the back upper portions) and the components of the adjustment mechanisms (e.g., the track and/or the mount) are molded as a single unit in a single cavity. In other embodiments, insert molding may be used to combine prefabricated parts (e.g., the track and/or the mount) with the molded parts (e.g., the uppers) during the molding process.

In another exemplary embodiment hereof, the components of the adjustment mechanism (e.g., the track and the mount) may be produced fully configured, with the mount properly placed on the track, during the molding process.

In another exemplary embodiment hereof, the footwear 100 and the associated adjustment mechanisms are formed fully configured using a single molding process.

1. Molding the Elements Together

In exemplary embodiments hereof, the upper, the adjustment mechanism (including the track and/or the mount) and the sole may be molded using known molding techniques (e.g., injection molding, compression molding, over molding, insert molding, centrifugal molding, foaming, and any combination thereof). The upper and the sole may be molded together as a single piece or molded separately and configured together thereafter. The footwear may be molded using polyurethane (PU), ethylene-vinyl acetate (EVA), other types of elastomers, artificial rubbers, polymers, rubbers, plastics and/or other suitable materials and any combination thereof.

If any of the parts require distinct materials, over molding may be used.

2. Insert Molding the Elements

In some exemplary embodiments hereof, the rail and/or the slider may be produced separately and then insert molded with the back upper portion and/or the front upper portion during the molding process. The rail and/or the slider may be produced using a different mold, an extrusion die and/or a different manufacturing process.

The slider may be formed with the front upper portion using insert molding in a similar manner.

3. Producing Fully Configured Footwear

In one exemplary embodiment hereof, the mount is molded in position on the track during the molding process of the footwear. This may require the use of one or more insert areas as well as one or more additional mold sliders within the mold.

In one exemplary implementation of this embodiment, the rail may be molded as part of the back upper portion as described above, the slider may be molded as part of the front upper portion, and the slider may be configured on the rail during the molding process.

In another exemplary implementation of this embodiment, the rail may be molded as part of the back upper portion as described above, the slider be insert molded with the front upper portion, and the slider may be configured on the rail during the molding process.

The result is a rail molded as part of the back upper portion, a slider insert-molded with the front upper portion, and the slider configured onto the rail.

In another exemplary implementation of this embodiment, the slider may be configured onto the rail and the combination may be insert molded with the back upper portion and/or the front upper portion.

The result is a rail insert molded with the back upper portion, a slider insert-molded with the front upper portion, and the slider configured onto the rail.

In the embodiments described herein, the sole may be molded in combination with the footwear and the adjustment mechanism to form a fully configured footwear. Alternatively, the sole may be produced separately and attached to the other molded parts to create a fully configured footwear.

It is understood that not all of the acts or steps disclosed in the manufacturing processes in any of the embodiments must be taken. For example, the slider may be configured on the rail during the molding process but may not necessarily be configured with the front upper portion during the process. Instead, the slider may be configured with the front upper portion after the molding process (e.g., by stitching).

CONCLUSION

A person of ordinary skill in the art will understand, upon reading this specification, that the manufacturing processes described herein are meant for demonstrational purposes and are not all-inclusive, and that other manufacturing processes and/or additional steps not disclosed may be used and/or taken to accomplish the same or similar outcomes.

Where a process is described herein, those of ordinary skill in the art will appreciate that the process may operate without any user intervention. In another embodiment, the process includes some human intervention (e.g., a step is performed by or with the assistance of a human).

As used herein, including in the claims, the phrase “at least some” means “one or more,” and includes the case of only one. Thus, e.g., the phrase “at least some ABCs” means “one or more ABCs,” and includes the case of only one ABC.

As used herein, including in the claims, the term “at least one” should be understood as meaning “one or more,” and therefore includes both embodiments that include one or multiple components. Furthermore, dependent claims that refer to independent claims that describe features with “at least one” have the same meaning, both when the feature is referred to as “the” and “the at least one.”

As used in this description, the term “portion” means some or all. So, for example, “A portion of X” may include some of “X” or all of “X.”

As used herein, including in the claims, the phrase “using” means “using at least,” and is not exclusive. Thus, e.g., the phrase “using X” means “using at least X.” Unless specifically stated by use of the word “only,” the phrase “using X” does not mean “using only X.”

In general, as used herein, including in the claims, unless the word “only” is specifically used in a phrase, it should not be read into that phrase.

As used herein, including in the claims, the phrase “distinct” means “at least partially distinct.” Unless specifically stated, distinct does not mean fully distinct. Thus, e.g., the phrase, “X is distinct from Y” means that “X is at least partially distinct from Y,” and does not mean that “X is fully distinct from Y.” Thus, as used herein, including in the claims, the phrase “X is distinct from Y” means that X differs from Y in at least some way.

It should be appreciated that the words “first” and “second” in the description and claims are used to distinguish or identify, and not to show a serial or numerical limitation. Similarly, the use of letter or numerical labels (such as “(a),” “(b),” and the like) are used to help distinguish and/or identify, and not to show any serial or numerical limitation or ordering.

As used herein, including in the claims, the terms “multiple” and “plurality” mean “two or more,” and include the case of “two.” Thus, e.g., the phrase “multiple ABCs,” means “two or more ABCs,” and includes “two ABCs.” Similarly, e.g., the phrase “multiple PQRs,” means “two or more PQRs,” and includes “two PQRs.”

The present invention also covers the exact terms, features, values and ranges, etc. in case these terms, features, values and ranges etc. are used in conjunction with terms such as about, around, generally, substantially, essentially, at least etc. (i.e., “about 3” shall also cover exactly 3 or “substantially constant” shall also cover exactly constant).

As used herein, including in the claims, singular forms of terms are to be construed as also including the plural form and vice versa, unless the context indicates otherwise. Thus, it should be noted that as used herein, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise.

Throughout the description and claims, the terms “comprise,” “including,” “having,” and “contain” and their variations should be understood as meaning “including but not limited to,” and are not intended to exclude other components unless specifically so stated.

It will be appreciated that variations to the embodiments of the invention can be made while still falling within the scope of the invention. Alternative features serving the same, equivalent, or similar purpose can replace features disclosed in the specification, unless stated otherwise. Thus, unless stated otherwise, each feature disclosed represents one example of a generic series of equivalent or similar features.

Use of exemplary language, such as “for instance”, “such as”, “for example” (“e.g.,”) and the like, is merely intended to better illustrate the invention and does not indicate a limitation on the scope of the invention unless specifically so claimed.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Part Numbers Part Number footwear 100 front 106 side 110 right side 112 sole 114 upper 116 front upper portion 122 upper portion 124 top opening 126 edge 128 front edge 130 Rail/track 134 ridge 136 segment 138 end piece 140 outer surface 142 tab 202 mount 204 ring 206 inner opening 208 slot 210 slide locking mechanism 212 tooth 214 tab 222 portion 224 hole 226 hole 228 stud 230 base 406 slot 514 recess 516 post 518 head 520 rail 734 slide portion 736 

1. A shoe comprising: a rear portion and a front portion having at least one gap therebetween, wherein relative positions of the rear portion and the front portion define a size of the shoe; and a rail configured with the rear portion; and a slider configured with the front portion, the slider engaging the rail, wherein the rail provides multiple distinct and discrete positions for the slider, and wherein a position of the slider in the rail determines a size of the at least one gap, and wherein the front portion and the rear portion comprise molded plastic, and wherein the rail is molded in the rear portion.
 2. The shoe of claim 1, wherein the rail has a circular cross section.
 3. The shoe of claim 1, wherein the rail includes a plurality of ridges, said ridges defining said multiple distinct and discrete positions for the slider.
 4. The shoe of claim 1, further comprising a sole, and wherein the rail is at a non-zero angle to a base of the sole.
 5. The shoe of claim 1, further comprising a sole, and wherein the rail is parallel to a base of the sole.
 6. The shoe of claim 2, wherein the rail includes a plurality of ridges, said ridges defining said multiple distinct and discrete positions for the slider.
 7. The shoe of claim 2, further comprising a sole, and wherein the rail is at a non-zero angle to a base of the sole.
 8. The shoe of claim 2, further comprising a sole, and wherein the rail is parallel to a base of the sole.
 9. Footwear comprising: a rear portion and a front portion having at least one gap therebetween, wherein relative positions of the rear portion and the front portion define a size of the footwear; and a rail configured with the rear portion; and a slider configured with the front portion, the slider engaging the rail; and a sole, wherein the rail provides multiple distinct and discrete positions for the slider, and wherein a position of the slider in the rail determines a size of the at least one gap, and wherein the front portion and the rear portion comprise molded plastic, and wherein the rail is molded in the rear portion, and wherein the rail has a circular cross section, and wherein the rail includes a plurality of ridges, said ridges defining said multiple distinct and discrete positions for the slider.
 10. The footwear of claim 9, wherein the rail is at a non-zero angle to a base of the sole.
 11. The footwear of claim 9, wherein the rail is parallel to a base of the sole.
 12. Footwear comprising: a rear portion and a front portion having at least one gap therebetween, wherein relative positions of the rear portion and the front portion define a size of the footwear; and a rail configured with the rear portion; and a slider configured with the front portion, the slider engaging the rail; and a sole, wherein the rail provides multiple distinct and discrete positions for the slider, and wherein a position of the slider in the rail determines a size of the at least one gap, and wherein the front portion and the rear portion comprise molded plastic, and wherein the rail is molded in the rear portion, and wherein the rail includes a plurality of ridges, said ridges defining said multiple distinct and discrete positions for the slider.
 13. The footwear of claim 12, wherein the rail is at a non-zero angle to a base of the sole.
 14. The footwear of claim 12, wherein the rail is parallel to a base of the sole. 